2.4 JUNCTION BREAKDOWN
when a sufficiently high field is applied to a p-n junction, the junction breaks down and conducts a very large current 11. Breakdown occurs only in the reverse-bias regime because high voltage can be applied resulting in high field. There are basically three breakdown mechanisms: (1) thermal instability, (2) tunneling, (3) avalanche multiplication . We consider the first two mechanisms briefly, and discuss avalanche multiplication in more detail.